If your phone is showing very small text, select "phone" to force pages to be shown appropriately for a phone. Similarly with "tablet" or "desktop".

Why isn't this always just automatic?

This website automatically changes the way pages are displayed based on the device it is being displayed on. The design may be different on a phone vs. a tablet vs. a desktop computer.

Automatic selections are made based on limited available data, particularly the number of pixels in the display. Today, however, many phones have the same pixel width and height as tablets or desktop windows. When the pixel size is saying "tablet" or "desktop" but the device is a phone, you'll see unreadably small text.

However, you can override the automatic device guesses by selecting "phone", "tablet" or "desktop" in this menu.